Three-layer nickel laminate



Nov. 28, 1967 u ROSE ET AL 3,355,263

A I THREE-PLAYER NICKEL LAMINATE Filed Nov. 1 0, 1964 CHROMIUM PLATE BRIGHT NICKEL PLATE I NICKEL-SELENIUM ALLOY PLATE (am-azmu, 01% 4% SELEN/UM) NICKEL PLATE METAL BASE CHROMIUM PLATE BRIGHT NICKEL PLATE NICKEL-SELEN|UM ALLOY PLATE (0.0/0.2MIL., 0I/%-4% SELEN/UM) NICKEL PLATE METAL BASE AIZTH U12 H. DURME mm WILLIAM J. PIERCE INVENTORS desired amount of selenium.

United States Patent Ofiice 3,355,263 THREE-LAYER NICKEL LAMINATE Arthur H. Du Rose, Euclid, and William J. Pierce,

Cleveland, Ohio, assignors, by mesne assignments, to Kewanee Oil Company, Bryn Mawr, Pa., a corporation of Delaware Filed Nov. 10, 1964, Ser. No. 410,062

' 11 Claims. (Cl. 29183.5)

ABSTRACT OF THE DISCLOSURE This invention relates to a composite coating of adjacently bonded layers of nickel and more particularly to a composite coating of three layers wherein an intermediate layer thereof comirses a thin nickel deposit containing a In recent years much work has been done to provide an article with a decorative plate of chromium over two or moreunderlying layers of nickel. The composition and electrochemical properties of these layers of nickel are de- Signed to obtain as good protection of the base surface against corrosion as possible without compromising the decorative appearance.

When using three layers of nickel, the composition of the intermediate layer is adjusted so as to be anodic to both the upper and lower layers and preferably the composition of the upper layer is adjusted so as to be anodic to the lower layer.

By the use of some triple-layer systems, marked corrosion protection was effected (see Knapp, Trans. Inst. Met. Finishing, 1958, 35, 139-165). In most cases, however, the metal corroded too rapidly causing blistering or scaling or staining or colored the decorative surface.

Within the last few years triple-layer systems have been made using a nickel-containing deposit for each of the three layers. Relative potentials of the layers have been controlled by the amounts of sulfur deposited with the nickel. The sulfur may be controlled in the deposits by adjusting the contents in the bath of the various organic brightening additives comprising sulfur with or without additional sulfur-containing compounds. Sulfur-free brighteners with sulfo-oxygen carriers also may be used to supply some or all of the sulfur in the bath and hence in the nickel deposit. Thus, control of the addition agents in the bath may ultimately control or partly control the amount of sulfur in the electrodeposits and thereby the relative potentials of the deposits.

Several problems have arisen in connection with the triple-layer system because sulfur as such not only proin some instances e.g. 10%

Patented Nov. 28, 1967 vides differences in potential in electro-deposits of nickel but also affects other physical properties such as ductility and brightness and continuity of the deposit. For instance, if the proper potential is to be maintained between the intermediate layer and the top layer, the sulfur contents of each layer must be controlled. However, the sulfur content of sulfur-containing nickel is limited and the potential tends to level off at sulfur concentrations in the range of from about 0.2-0.3 percent by weight. Thus the degree in which the concentration of sulfur in the deposits may be varied in the nickel layer to adjust potential is very narrow. Moreover, if a plater prefers to deposit a lower layer of nickel from a sulfur-containing bath, he may have to increase the amounts of sulfur in the intermediate and upper nickel layers.

It has now been discovered that in triple layer systems having selenium-containing intermediate layers, such selenium-containing layers are strongly anodic to customary nickel deposits and can be used effectively as sacrificial layers in the three-layer group, nickel, nickel-selenium, nickel. Such layers may be deposited from any common nickel plating bath, such as a standard Watts type bath having the proper concentration of a water-soluble selenium compound.

In accordance with the present invention there is provided an improved composite coating comprising three adjacently bonded layers of nickel deposits, the lower layer being a conventional low-sulfur or sulfur-free nickel electroplate preferably 0.3 to 2 mils thick and having from 0 to about 25 percent, preferably from about .1 percent to about 25 percent cobalt by Weight alloyed therewith and a sulfur content preferably less than 0.01 percent; a top layer of a conventional bright nickel electroplate preferably 0.15 to 1 mil thick and having from 0 to 50 percent preferably about .1 to about 50 percent cobalt alloyed therewith and preferably from about 0.03 percent to about 0.3 percent sulfur by weight; and an percent cobalt alloyed therewith and containing from about 0.1 percent selenium to about 4 percent selenium based on the total weight of said intermediate deposit. Larger amounts of selenium may be used by Weight of said second electrodeposit. Sulfur in the necessary but can be present in for the lower layer. The term alloy is used herein to include codeposit and the term alloyed is used toin-' elude codeposited. Preferably the selenium concentraquantity such as indicated tion in the intermediate layer is kept in the range of from about 0.10 percent to about 2.5 percent. It is not necessary to have a cobalt content in the nickel but it can be used and commercial nickel often contains it up to 0.5

equivalent of nickel up to the above stated percentages for the purposes of this invention.

The mechanism by which the triple-layer coating system of the present invention is believed to protecta corintermediate layer is not rodible substrate may be more easily understood by re ferring to the accompanying drawings in which:

FIG. 1 illustrates schematically a triple-layer system with a corrosion pit which has not yet penetrated the intermediate layer.

FIG. 2 illustrates the same triple-layer system with the corrosion pit where the pit has reached and has attacked the intermediate layer.

FIG. 3 illustrates the same triple-layer system with the corrosion pit widened laterally but where the lower layer has not been attacked substantially. These figures represent what is believed a typical modus operandi for corrosion pitting.

The composite electroplate of the present invention advantageously is employed over various substrates and particularly metal substrates susceptible to corrosion. Iron, steel, copper, brass, aluminum, zinc and magnesium with or without a copper deposit, are substrates protected by the composite electroplates of the present invention.

The selenium present in the intermediate layer of the instant triple-layer composites provides good corrosion protection to the substrate covered by the system. The electroplate composites of the present invention are more effective than those using sulfur in the intermediate layer.

Corrodkote is the name given to an accelerated test in which a synthetic road soil slurry is applied to the plated surface of an article and the article is then exposed to a warm humid atmosphere. A Corrodkote slurry formulation includes both soluble and insoluble elements and sufiicient liquid to give proper spreading consistency. The slurry is applied to the surface being tested by means of a paint brush, or similar device, to produce a fairly uniform coating, after which the coated specimen is eX- posed to specifiedhurnidity conditions.

A standard Corrodkote mixture, effective in testing chromium-nickel combinations over steel, is:

Kaolin -a grams 30 Ferric chloride do 0.165 Cupric nitrate do 0.035 Ammonium chloride ..do 1 Water ml 50 The CASS test involves exposing the plated parts to a salt spray containing small concentrations of cupric chloride and acetic acid.

Both the Corrodkote and the CASS tests have been accepted by the industry as well established accelerated tests for corrosion. For a complete description of the tests see Plating, vol. 44, p. 763, 1957.

In some instances neither the Corrodkote test nor the CASS test are absolutely reliable in predicting service life of plated parts on cars. Where some plated panels are rated good by the Corrodkote test, the same panels are less highly rated by the CASS test and the reverse would be observed with the other plated panels. Therefore the test results set forth hereinafter to show the advantages of the present invention are obtaind by submitting the sample panels to 3 or 4 Corrodkote cycles, and instead of using more Corrcdkote cycles, further submitting the panels to the CASS test. Controls or panels for comparison are always employed. A representative test would be 3 or 4 Corrodkote cycles plus 48 hours of CASS exposure.

The advantage of using the triple-layer composite systems to protect a corrodible substrate becomes significant when reference is made to FIGS. l-3 of the drawing. These figures illustrate in sequence the progressive corrosion of a three-layer composite according to the invention. As a corrosion pit is for-med in the top nickel layer as shown in FIG. 1 (through a pore or other defeet in the chromium decorative coat), the pit progressively enlarges hemispherically. This corrosion site continually, enlarges until it reaches the more anodic intermediate layer.

In the triple-layer system the intermediate layer acts as the sacrificial anode primarily, while the top layer provides the bright surface for the decorative chromium; the composition of the intermediate layer need not be controlled as rigidly as the composition of the top layer in a duplex system.

As mentioned hereinbefore, the triple-layer system is most effective when the intermediate layer is anodic to the lower layer and the upper layer and wherein the lower layer is cathodic to the upper layer. The intermediate layer acts as a primary sacrificial anode and the upper layer acts as a secondary sacrificial anode, protecting the lower layer. The use of selenium as the alloying constituent with nickel in the preparation of the intermediate layer provides higher potentials. than those in deposits prepared by the use of sulfur as the alloying constituent with nickel.

In order to carry the present invention into effect, the substrate is plated first with a lower layer of nickel and then with the intermediate layer of nickel and the upper layer of nickel. Any solution of nickel ions designed for electroplating nickel may be used.

The solutions should contain at least one of the following salts: nickel sulfate, nickel chloride, nickel fluoroborate and nickel sulfamate, wherein the solution is adjusted to an operating concentration of nickel. Included among the various baths useful in carrying out the present invention are (1) the various barrel plating baths generally comprising nickel sulfate and nickel chloride as the source of the nickel ion and buffer systems, for example, boric acid, (2) the all-chloride bath designed for use where a high current density is desired, comprising nickel chloride as the source of nickel ion and boric acid as the buffer, (3) the fiuoroborate bath comprising nickel fluoroborate as the source of nickel ion and free boric acid as the buffer alone or in combination with fluoroboric acid, (4) the common Watts-type bath designed for all purpose nickel plating and generally comprising nickel sulfate and nickel chloride as the source of nickel ion buttered with boric acid, (5) the all sulfamate bath comprising nickel sulfamate including boric acid as the buffer, (6) the chloride-sulfamate bath comprising nickel chloride and nickel sulfamate with boric acid as the butter, and (7) other nickel baths made from nickel salts and complexing agents.

After the desired thickness is obtained for the first or lower layer of nickel, the selenium-containing intermediate layer of nickel is deposited. A selenium-supplying compound is added to one of the above named baths, the bath is adjusted to the appropriate concentration and a thin layer of selenium-containing nickel is deposited directly on the surface of the first or lower layer of nickel.

The composite is then completed by plating a third deposit of nickel directly on the surface of the intermediate plate. Normally this plate is fully bright to provide an optimum surface for the decorative chromium plate. The decorative chromium layer advantageously is from about 0.005 mil to about 0.2 mil thick. Each of the above layers of nickel may be deposited using more than one step such as, for example, by interrupting the plating cycle.

In its preferred form the composite coating of the present invention comprises a first or lower layer of ductile sulfur-free nickel. This preferred plate is deposited from a typical Watts-type or fluoroborate-type bath containing an effective amount of a sulfur-free leveler such ascoumarin or the like. The top layer of nickel preferably being fully bright is deposited from one of the above baths using a brightener of the first class (sulfooxygen carrier) and a brightener of the second class. Where the top layer is higher in sulfur content (0.1 to 0.3 percent) the lower layer also may be deposited from a bath containing in addition to a brightener of the first class (sulfo-oxy-gen compound) small amounts of a 7 brightener of the second class. The baths disclosed in U.S. Patent 3,090,733 are useful for preparing the upper layers of nickel in the composite disclosed and claimed therein may be used to deposit the upper layers of nickel for the present invention.

As indicated hereinbefore, the lower and top layers of nickel may be deposited from baths of conventional compositions and in the baths there may be present one or more brighteners of the first class. These compounds generally comprise an aryl ring, a substituted aryl ring or an unsaturated aliphatic chain with a sulfur-containing radical in the form of sulfonic acids, sulfonates, sulfonamides, sulfimides, sulfinic acid and sulfones. The aryl ring advantageously may be .derived from v.benzene, napthalene and the like, the substituted aryl ring may be derived from toluene, xylene, napthylamine, toluidine, benzyl naphthalene and the like and the alkylene chain may advantageously be derived from vinyl compounds or allyl compounds and the like. Examples of sulfo-oxygen compounds of the above described type and which are useful particularly in the instant nickel plating baths are found in U.S. Patents 2,757,133 and 2,766,284.

Almost uniformly, the top layer of nickel is deposited from baths containing, in addition to brighteners of the first class, brighteners of the second class including organic compounds such as the various ketones, aldehydes,'carboxylic acids, some proteins (gelatin) and the like; compounds such as the alkylenic carboxylic esters, the alkylenic aldehyde, the aromatic compounds such as the aryl aldehydes, the sulfonated aryl aldehydes, allyl and vinyl substituted compounds, coumarin and its derivatives, and the like; .those compounds having acetylenic radicals (CEC including the acetylenic alcohols; nitrogen heterocyclics having' an N-substituted acetylenic radical and the like; those compounds such as the azine, thiazine and oxazine dyes, the triphenyl methane dyes, the quinidines, pyrimidines, pyrazoles and imidazoles, the pyridinium and quinolinium compounds, and the like; those compounds such as the nitriles, thionitriles and the like; and those compounds having the thioureide radical (NCES) such as the cylic thioureides and thiourea.

Compounds considered useful as brighteners of the second class include the water-soluble aceytlenic compounds set forth in U.S. Patent (Kardos et el.) 2,712,522; the aryl, alkylene and arylalkynoxy sulfonic acids set forth in U.S. Patent 2,800,442; the alkynoxy sulfonic and carboxylic acids having the triple bond separated from the acid radical by at least one oxygen atom set forth in U.S. Patent 2,841,602; and the nitriles set forth in U.S. Patents 2,524,010; 2,647,866; 2,882,208; 2,978,391 and 3,093,557.

' Where cobalt is desired as an alloying constituent in the nickel layers, the instant bath may be adjusted by adding any of the cobalt salts well known to those skilled in the art. For example, the halides of cobalt are particularly useful including cobalt chloride, cobalt bromide, and the like. Cobalt sulfate may be used also.

Nickel electroplating baths particularly useful in combination with these brightener systems include the Wattstype and'fluoroborate-typebaths having increased nickel content. Such baths are designed for use with organic brighteners in general; they may be operated at the higher current densities desirable for the effective use of the organic brighteners. The preferred Watts-type bath essentially comprises an overall nickel content ranging from 70 to 115 grams per liter provided by 270 grams per liter to about 450 grams per liter of nickel sulfate and from about 20 grams per liter to about 90 grams per liter of nickel chloride with about 30 to 40 grams per liter of boric acid as the buffer and the preferred fluoroboratetype bath essentially comprises an over-all nickel content ranging from 75 to 110 grams per liter with about 30 grams perliter .of boric acid as the buffer.

For purposes of the present invention, boric acid is preferred as the buffer-as an additive to maintain the desired pH. However, acetic acid, borax (sodium tetraborate), formic acid, the fluoroborates, and other compounds commonlyknown to have utility as buffers, may be used with the baths of the present invention with no apparent undesirable effects.

Illustrative examples of wetting agents wlzu'ch may be employed in the baths for carrying out the present invention include a great number of the anionic surfactants. The sulfate type particularly may be used. Included among this type are certain of the alkylsulfates, aralkylsulfates, alkylsulfonates, and aralkylsulfonates.

The use of wetting agents in baths used in carrying out the present invention is desirable but optional; acceptable deposits areoften obtained from baths having no wetting agent therein.

We have found that the amount of a selenium-containing compound which is of use in preparing our seleniumnickel intermediate layer electrodeposit depends on the valence of the selenium in the compound used in preparing the electroplating bath.

If selenium dioxide, or other selenium-containing compound, is used which provides selenite ions (SeO in the electroplating bath, we may add 0.05 to 3 grams per liter of SeO (or its equivalent amount if another compound is used), and preferably 0.1 to 1 gram per liter of selenium dioxide (or its equivalent). With larger amounts of selenium dioxide, the deposits tend to become rough and spongy.

If we use sodium selenate (or other compounds giving selenate ions [SeO in solution) large amounts may be used up to 40 grams per liter or more, up to saturation. Large amounts are not required, however, and we prefer to use 0.2 to 5 grams per liter of sodium selenate.

Any of the above described nickel plating baths (Watts, fluoroborate, etc.) may be used with the added selenium compound. The optimum amount of the particular selenium-supplying compound necessary to impart an optimum amount of selenium in the nickel deposit varies with each compound; and, of course, the temperature of the bath and cathode current density vary the deposits. Moreover, many selenium-containing compounds which could be used to impart selenium into the nickel deposit are not very soluble in water and this limits the amounts which can be used.

Preferably, the operating temperature of a typical bath (Watts-type) is in the range of from about 130 F. to about 150 F. This range is not critical, however, and good deposits may be obtained at temperatures as low as 50 F. or as high as 180 F. or even at the boiling point of the electrolyte. Where the Watts-type bath is employed, current densities ranging from about 10 to 50 I amperes per square foot are preferred. The pH should be in the range of from 1.5 to 5.5 and preferably in the range of from 4 to 5.

Selenium may be added to the bath used in carrying out the present invention in the form of selenic acid, selenous acid, sodium, potassium, cobalt and nickel selenates and selenites, or asv organic compounds containing selenium provided selenite or selenate ions are formed in solution. 1

As a further feature of the present invention a sulfooxygen compound or brightener of the first class is added to the selenium-containing bath in small amounts. The selenium may be present in any form. which will provide selenate or selenite ions. The sulfo-oxygen compound acts to provide a semibright deposit of enhanced lustre. The concentrations of the sulfo-oxygen carrier useful in forming the deposits are from about 0.5 gram per liter'to about 2 grams per liter of the sulfo-oxy-gen compound, but amounts outside this range are useful also. It has been found that relatively small amounts of sulfur are imparted into the deposit by these sulfo-oxygen compounds, an amount which is much less than is obtained in the deposit from a fully bright nickel bath containing a brightener of the second class. Y

The following Table A sets forth specific compositions of baths useful for depositing the lower layer in preparing the triple-layer composite electroplate of the present Table B. After rinsing again an approximately millionth of an inch layer of chromium was plated on the invention: upper surface of the top layer. The amount of selenium TABLE A Boric Bath Nickel Salts, g./l. Addition Agent, g./l. Other Additives, g./l. Wetting Agents, g.ll. BAKETid pH u er, el

la NiSQrGHzO, 300; Sodium lauryl sulfate, 0.02 37 3. 5

NiC-l .6H20, 37.

2a NlSO-l-GIIZO, 300; Couinarin, 0.2 Formaldehyde 0.1 cc./l do 37 4.0

NiCl2.6lIzO, 37.

3a NlSO-LfiHzO, 300; Nickel Formate, 4.5... Formaldehyde, 0.5 cc./l 30 2. 5

NiClz.6Hz0, CoSOmIhO, 30.

4a NiSOMHgO, 150; 3 Broniocournarin, 0.2... 30 4.0

NiClz.6H2O, 150.

5a NiSOifiHiO, 300; Butynediol, 0.1 Chloral, 0.05 30 4. 0

.NiCh-GHzO, 30.

6a NiSO4. 6H20, 300; Coumarin, 0.1 Formaldehyde (10%), 0.1 ce./l.; Sodium octyl sulfate, .1 35 4. 0

NiOlz.6H-zO, 30. Sacchat'in 1.0.

7a NiisgBFm, 300; NiClz.6Hz0, Coumarin, 0.2 Chloral, 0.05 d0 35 3.5

The following Table B sets forth specific compositions of baths useful for depositing an upper layer or top layer in preparing the triple-layer composite electroplate of the present invention:

in the above intermediate layer was about 1.0% by weight. The lower layer contained almost no sulfur while the top layer contained about 0.09% sulfur by weight.

The resulting deposit was bright and corrosion resistant.

TABLE B Borie Ex. No. Nickel Salts, g./l. Organic Sulfo-oxygen cpd, g./l. Brighteners, g./1. Wetting Agents, g./l. Bmtafid pH 11 er, g./l.

1b- Ni so i clg o ago; Naphthalenedisuli'onie acid, 4. Reduced fuchsin, .007 Sodium lauryl sulfate, 0.03.- 37 3. 5

i z. 1 7. 2b- NiSO4fiH20, 300; Saccha'rin, 1; Allyl' sulionate Butynediol, 0.2; do 37 4.0 Nick-61130, 37. 0.5. Coumarin, 0.1. 3b N iSO4;6HaO, 300; Dibenzenesulfonimide, 3 Allylpyridinium .do 37 4. 0

NiClz.6Hz0, 37. bromide, 0.05. 4h. NiSO4.6H20, 300; p,p' oxy-bis(dibeuzenesulfon- B,B thiodipropionitrile, Sodium octyl sulfate, 0.1 37 4. 0 NiCl2.6H2 37 amide), 3. 0.003. 5b. NlSOi-GHzO, 150, Saecharin, 2, Allyl sulfonate, do 37 3. 5

N1Clz.GHzO, 150. 1. 6b. Ni[(NHz)SO4];,.400; Same as 213 Same as 2b Same as 1]) 37 4. 0

NiClrnfiHiO, 15. NiSO4.6HzO, 300', Benzenesulfonamide, 2 Same as 1b 37 3. 5

, NiCl fiHgO, 40.

Following are examples of tests of the invention: E xdmple ll Example I Using bath 2a from Table A, a 0.5 mil layer of nickel kept at a temperature of about 140 F. and a pH of about 4.0.

Bath constituents:

NiSO' .6H- O NiCl .6H O Boric acid (H BO Na SeO Water to make 1000 ml.

Grams per liter (approx.) 300 45 45 0.42

The panel was rinsed againand a 0.4 mil top or upper layer of bright nickel was deposited from bath 4!; of

This example varies from Example I mainly in that Constituents:

the sodium selenate in the bath is increased to 0.85 ,g./l.

Grams per liter Water to make 1000 cc.

The selenium-containing deposit contained about 1.5

selenium as against about 1.0 by weight in Example I.

Example III This example varies from Example I mainly in that the amount of sodium selenate in the bath is 1.70 grams per liter. The percentage of selenium in the deposit is about 2.4%. At 4.2 grams of sodium selenate per liter of solution the selenium-containing deposit was about 3.3% selenium. At 8.5 grams of sodium selenate per liter of solution, the selenium-containing deposit was about 3.4% selenium. Thicknesses of deposits remain substantially the same and the same high corrosion resistance is found.

Example IV Same as Example 1, except that 0.09 g./l. Se replaces Na SeO giving .18% Se in the deposit.

Example V Same except use 0.16 g./l. 8e0 gives 2.6% Se in the deposit.

Example VI Same except use .32 g./l. Se0 gives 0.7% Se in the deposit.

The present invention also includes composites or laminates of nickel having more than three layers of nickel and composites or laminates wherein the manganesenickel layer is sandwiched between layers of nickel which will have relative potentials equal substantially to each other and more cathodic than the intermediate layer.

The amounts of selenium compound shown are for Na SeO and other compounds should be calculated as molecularly equivalent.

What is claimed is:

1. As a new article of manufacture, a laminated coating comprising a first nickel layer on a metal base to be protected, a second nickel electrodeposit consisting essentially of 0.1-10 percent by weight of selenium and overlying said first nickel layer and a third nickel layer overlying said second nickel layer, said first nickel layer being firmly bonded to said base, said second nickel layer being firmly bonded to said first nickel layer and said third nickel layer being firmly bonded to said second nickel layer.

2. The new article of manufacture as defined in claim 1 further characterized in that said layers have a portion of the nickel replaced by cobalt and the second nickelcobalt layer contains selenium.

3. The new article of manufacture as defined in claim 10 1 further characterized in that in said second layer a portion of the nickel is replaced by a minor portion oi cobalt.

4. As a new article of manufacture the invention defined in claim 1 wherein the said second layer is from 0.01 to 0.2 mil thick.

5. As a new article of manufacture the invention defined in claim 1 wherein the said second electrodeposit is from 0.01 to 0.2 mil thick and the said second electrodeposit contains from 0.1 to 4% selenium by weight.

6. The new article of manufacture as defined in claim 2 wherein the first layer has a thickness from 0.3 to 2 mils and has less than 0.01% sulfur by weight, the third layer has a thickness of from 0.15 to 1 mil, the nickel in said third layer having 0.03 to 0.3 percent sulfur by weight therein and said second layer having a thickness of from 0.01 to 0.2 mil and containing from about 0.1 to about 10 percent selenium by weight.

7. As a new article of manufacture a laminate comprising three firmly bonded layers of nickel including an intermediate layer of a nickel-selenium alloy between and firmly adherent to a selenium-free lower layer and a selenium-free upper layer.

8. The article of claim 4 wherein said top layer of nickel is electroplated with a chromium deposit having a thickness ranging from about 0.005 to about 0.2 mil, said lower layer being bonded to a substrate of the class consisting of iron, steel, copper, zinc, aluminum, magnesium and alloys thereof.

9. The article of claim 1 wherein the third layer of nickel is electroplated with a chromium deposit having a thickness from about 0.01 to 0.2 mil.

10. The article of claim 5 wherein the top layer of nickel is electroplated with a chromium layer having a thickness from 0.01 to 0.2 mil.

11. The article of claim 6 wherein further the third electrodeposited coating is coated with a layer of chromium of a thickness from 0.01 to 0.2 mil References Cited UNITED STATES PATENTS 3,288,574 11/1966 Du Rose 29-194 HYLAND BIZOT, Primary Examiner. 

1. AS A NEW ARTICLE OF MANUFACTURE, A LAMINATED COATING COMPRISING A FIRST NICKEL LAYER ON A METAL BASE OT BE PROTECTED, A SECOND NICKEL ELECTRODEPOSIT CONSISTING ESSENTIALLY OF 0.1-10 PERCENT BYW EIGHT OF SELENIUM AND OVERLYING SAID FIRST NICKEL LAYER AND A THIRD NICKEL LAYER OVERLYING SAID SECOND NICKEL LAYER, SAID FRIST NICKEL LAYER BEING FIRMELY BONDED TO SAID BASE, SAID SECOND NICKEL LAYER BEING FIRMLY BONDED TO SAID FIRST NICKEL LAYER AND SAID THIRD NICKEL LAYER BEING FIRMLY BONDED TO SAID SECON NICKEL LAYER. 